[PATCH v2 7/8] pc: Allow instantiating a virtio-iommu device

[Jean-Philippe Brucker]

From: Eric Auger <eric.auger@redhat.com>

Add a hotplug handler for virtio-iommu on x86 and set the necessary
reserved region property. On x86, the [0xfee00000, 0xfeefffff] DMA
region is reserved for MSIs. DMA transactions to this range either
trigger IRQ remapping in the IOMMU or bypasses IOMMU translation.

Although virtio-iommu does not support IRQ remapping it must be informed
of the reserved region so that it can forward DMA transactions targeting
this region.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 hw/i386/pc.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 694fc9ce07..c1e1cffe16 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -797,6 +797,11 @@ void pc_machine_done(Notifier *notifier, void *data)
                      "irqchip support.");
         exit(EXIT_FAILURE);
     }
+
+    if (pcms->virtio_iommu && x86_iommu_get_default()) {
+        error_report("QEMU does not support multiple vIOMMUs for x86 yet.");
+        exit(EXIT_FAILURE);
+    }
 }
 
 void pc_guest_info_init(PCMachineState *pcms)
@@ -1376,6 +1381,14 @@ static void pc_machine_device_pre_plug_cb(HotplugHandler 
*hotplug_dev,
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
                object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
         pc_virtio_md_pci_pre_plug(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
+        /* Declare the reserved MSI region */
+        char *resv_prop_str = g_strdup_printf("0xfee00000:0xfeefffff:%d",
+                                              VIRTIO_IOMMU_RESV_MEM_T_MSI);
+
+        qdev_prop_set_uint32(dev, "len-reserved-regions", 1);
+        qdev_prop_set_string(dev, "reserved-regions[0]", resv_prop_str);
+        g_free(resv_prop_str);
     }
 }
 
@@ -1393,6 +1406,11 @@ static void pc_machine_device_plug_cb(HotplugHandler 
*hotplug_dev,
         PCMachineState *pcms = PC_MACHINE(hotplug_dev);
         PCIDevice *pdev = PCI_DEVICE(dev);
 
+        if (pcms->virtio_iommu) {
+            error_setg(errp,
+                       "QEMU does not support multiple vIOMMUs for x86 yet.");
+            return;
+        }
         pcms->virtio_iommu = true;
         pcms->virtio_iommu_bdf = pci_get_bdf(pdev);
     }
@@ -1436,7 +1454,8 @@ static HotplugHandler 
*pc_get_hotplug_handler(MachineState *machine,
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) ||
         object_dynamic_cast(OBJECT(dev), TYPE_CPU) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
-        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
+        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI) ||
+        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
         return HOTPLUG_HANDLER(machine);
     }
 
-- 
2.33.0